We have studied the capability of He+ focused ion beam (He+-FIB) patterning to fabricate defect arrays on the Si/SiO2/Graphene interface using a combination of atomic force microscopy (AFM) and Raman imaging to probe damage zones. In general, an amorphized 'blister' region of cylindrical symmetry results upon exposing the surface to the stationary focused He+ beam. The topography of the amorphized region depends strongly on the ion dose, DS , (ranging from 103 to 107ions/spot) with craters and holes observed at higher doses. Furthermore, the surface morphology depends on the distance between adjacent irradiated spots, LS . Increasing the dose leads to (enhanced) subsurface amorphization and a local height increase relative to the unexposed regions. At the highest areal ion dose, the average height of a patterned area also increases as ?1/LS . Correspondingly, in optical micrographs, the ?m2-sized patterned surface regions change appearance. These phenomena can be explained by implantation of the He+ ions into the subsurface layers, formation of helium nanobubbles, expansion and modification of the dielectric constant of the patterned material. The corresponding modifications of the terminating graphene monolayer have been monitored by micro Raman imaging. At low ion doses, DS , the graphene becomes modified by carbon atom defects which perturb the 2D lattice (as indicated by increasing D/G Raman mode ratio). Additional x-ray photoionization spectroscopy (XPS) measurements allow us to infer that for moderate ion doses, scattering of He+ ions by the subsurface results in the oxidation of the graphene network. For largest doses and smallest LS values, the He+ beam activates extensive Si/SiO2/C bond rearrangement and a multicomponent material possibly comprising SiC and silicon oxycarbides, SiOC, is observed. We also infer parameter ranges for He+-FIB patterning defect arrays of potential use for pinning transition metal nanoparticles in model studies of heterogeneous catalysis.Metal oxide semiconductors such as ZnO have attracted much scientific attention due their material and electrical properties and their ability to form nanostructures that can be used in numerous devices. However, ZnO is naturally n-type and tailoring its electrical properties towards intrinsic or p-type in order to optimise device operation have proved difficult. Here, we present an x-ray photon-electron spectroscopy and photoluminescence study of ZnO nanowires that have been treated with different argon bombardment treatments including with monoatomic beams and cluster beams of 500 atoms and 2000 atoms with acceleration volte of 0.5 keV-20 keV. We observed that argon bombardment can remove surface contamination which will improve contact resistance and consistency. We also observed that using higher intensity argon bombardment stripped the surface for nanowires causing a reduction in defects and surface OH- groups both of which are possible causes of the n-type nature and observed a shift in the valance band edge suggest a shift to a more p-type nature. These results indicate a simple method for tailoring the electrical characteristic of ZnO.Photoplethysmography imaging (PPGI) has gained immense attention over the last few years but only a few works have addressed morphological analysis so far. Pulse wave decomposition (PWD), i.e. the decomposition of a pulse wave by a varying number of kernels, allows for such analyses. This work investigates the applicability of PWD algorithms in the context of PPGI.
We used simulated and experimental data to compare various PWD algorithms from the literature regarding their robustness against noise and motion artifacts while preserving morphological information as well as regarding their ability to reveal physiological changes by PPGI.
Our experiments prove that algorithms that combine Gamma and Gaussian distributions outperform other choices. Further, algorithms with two kernels exhibit the highest robustness against noise and motion artifacts (improvement in [Formula see text] of 14.09 %) while preserving the morphology similarly to algorithms using more kernels. Lastly, we showed that PWD can reveal physiological changes upon distal stimuli by PPGI.
This work proves the feasibility of pulse decomposition analysis in PPGI, particularly for algorithms with a low number of kernels, and opens up novel applications for PPGI. Not only for PPGI but for future research on PWD in general, our findings have importance as they elucidate differences between PWD algorithms and emphasize the importance of using initial values. To support such future research, we have released the algorithms and simulated data to the public.
This work proves the feasibility of pulse decomposition analysis in PPGI, particularly for algorithms with a low number of kernels, and opens up novel applications for PPGI. https://www.selleckchem.com/products/apo866-fk866.html Not only for PPGI but for future research on PWD in general, our findings have importance as they elucidate differences between PWD algorithms and emphasize the importance of using initial values. To support such future research, we have released the algorithms and simulated data to the public.Low dimensional systems, nanowires (NWs), in particular, have exhibited excellent optical and electronic properties. Understanding the thermal properties in semiconductor NWs is very important for their applications in electronic devices. In the present study, the thermal conductivity of a freestanding silicon NW is estimated by employing Raman spectroscopy. The advantage of this technique is that the excitation source (laser) acts as both the heater and probe. The variations of the first-order Raman peak position of the freestanding silicon NW with respect to temperature and laser power are recorded. From the analysis of effective laser power absorbed by exposed silicon NW and a detailed Raman study along with the concept of longitudinal heat distribution in silicon NW, the thermal conductivity of the freestanding silicon NW of ?112 nm diameter is estimated to be ?53 W m-1 K- 1.A graphene oxide (GO) membrane can be easily made by filtering a GO solution onto a supporting layer, and such a membrane is effective at adsorbing ions. But low flux and a high work pressure become an obstacle for its application in wastewater treatment. In this study, a positively charged mixture of carbon nanotubes and chitosan (CNTS) served as an interlayer to improve the GO membrane's flux. The three-layer membrane is known as MCG, while one without an interlayer is known as MG. For MCG and MG with the same GO load, the water flux of MCG reaches 2-8 times larger than that of MG. A better water permeability is consistently detected for MCG, with a contact angle descent speed of 3.3°/s, which is significantly faster than that of MG (0.5°/s). The ion rejections of MCG and MG are mostly attributed to GO adsorption, which stay at the same level. The flux varies with GO load, CNTS load and membrane dryness, while the ion rejection is correlated with the GO load. Optimized membrane fabrication conditions are suggested as being a CNTS load of 0.